Gas block and gas tube ferrule seal for firearms barrel

ABSTRACT

A gas block mounted to a rifle barrel and having a gas conducting tube retained within a tube receptacle of the gas block. A ferrule seat is defined about the gas conducting tube receptacle and a sealing ferrule member surrounding the barrel is press fitted within the ferrule seat and is deformed during press fitting to form a gas seal between the gas conducting tube and the gas block within the gas tube receptacle.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates generally to firearms, namely semi-automatic firearms, such as the M-16 and M-4 tactical rifles of the military and law enforcement and AR-15 tactical rifles that are widely used for sporting and match shooting activities. These firearms utilize a portion of the cartridge gas pressure that is generated within a rifle barrel upon cartridge firing to operate a mechanism for cartridge case extraction, ejection and fresh cartridge pickup and chambering. More particularly, the present invention concerns a gas block that is mounted to a rifle barrel at one or more barrel ports and defines a receptacle that receives and retains an end portion of a gas conducting tube member, permitting cartridge gas pressure received by passages of the gas block member from a barrel port to be conducted to a bolt carrier and bolt for pressure energized operational movement of the bolt carrier and bolt. Even more specifically the present invention concerns sealing apparatus for establishing a positive gas seal at the juncture of the gas conducting tube and the gas block.

Description of the Prior Art

M-16, M-4 and AR-15 tactical rifles are typically provided with a gas block member which has a tubular portion that receives a portion of a gun barrel and is positioned such that a gas conducting passage system of the gas block is in gas receiving communication with one or more holes or gas ports that intersect the bore of the barrel. When the rifle is fired, a portion of the cartridge gas is vented to gas conducting passage system from the rifle bore and is employed for gas pressure actuation of the cartridge handling system of the rifle. A gas conducting tube member that engages within a gas tube receptacle of the upper receiver of the firearm has an end portion that is retained within a gas tube receptacle of the gas block. The end portion of the gas tube is typically prepared to establish a relatively close fit within the gas tube receptacle. However, it has been determined that gas leakage often occurs at the gas tube/gas block interface. This gas leakage can dissipate some of the cartridge gas pressure in the gas handling system and interfere with proper gas energized operation of the bolt carrier and bolt mechanism, potentially preventing optimum operational characteristics of the firearm. Moreover, the hot, high pressure cartridge gas progressing within the gas block and gas conducting tube tends to be erosive, thus causing any gas leakage condition to worsen as the duration of firearm use progresses.

SUMMARY OF THE INVENTION

It is a principal feature of the present invention to provide a novel positive cartridge gas sealing system for the gas block and gas tube to ensure that cartridge gas leakage at the gas tube/gas block interface is prevented during firearm use.

It is another feature of the present invention to provide a novel gas block and gas conducting tube for a semi-automatic or automatic firearm that positively prevents gas leakage at the gas block/gas conducting tube interface during firing activity and thus ensures that the resulting cartridge gas is employed as efficiently as possible for operation of an autoloading firearm according to its technical design, promoting firearm efficiency, accuracy and control.

Briefly, the various objects and features of the present invention are realized by the provision of an autoloading firearm having a gas block that is mounted along the length of its firearm barrel in alignment with a gas passage that is in communication with the gas port of the barrel. The gas block defines a gas tube receptacle and further defines a gas tube seal receptacle that is located about the gas tube receptacle. A gas conducting tube is secured within the gas tube receptacle of the gas block by means of a retainer member that engages within aligned holes of the gas tube and gas block.

A deformable annular sealing ferrule is positioned about an end portion of the gas conducting tube and is press-fitted within the gas tube seal receptacle. During the press-fitting operation the gas tube sealing ferrule is deformed and establishes positive surface to surface sealing with the outer cylindrical surface of the gas conducting tube and with the internal surface geometry of the gas tube receptacle. The gas tube sealing ferrule prevents any cartridge gas leakage at the juncture or interface of the gas conducting tube and gas block.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features, advantages and objects of the present invention are attained and can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to the preferred embodiment thereof which is illustrated in the appended drawings, which drawings are incorporated as a part hereof.

It is to be noted however, that the appended drawings illustrate only a typical embodiment of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.

In the Drawings:

FIG. 1 is a side elevation view showing a rifle barred having a gas block and showing a portion of a cartridge gas tube being engaged within a gas tube receptacle of the gas block;

FIG. 2 is a longitudinal section view showing the rifle barrel and gas block of FIG. 1 and further showing an end section of a gas conducting tube engaged within the gas tube receptacle of the gas block;

FIG. 3 is an isometric illustration showing the top and one side of the gas block and gas conducting tube of FIGS. 1 and 2 and for purposes of simplicity omitting any showing of the rifle barrel structure;

FIG. 4 is an isometric illustration similar to FIG. 3 showing the bottom and a side of the gas block and gas conducting tube;

FIG. 5 is an exploded isometric illustration showing the gas block and gas conducting tube of FIGS. 1 and 2 and further showing a sealing ferrule positioned between the gas block and gas conducting tube;

FIG. 6 is an end elevation view showing the gas block and gas conducting tube of FIGS. 1 and 2;

FIG. 7 is a section view taken along line 6-6 of FIG. 5 and showing further details of the gas block and gas conducting tube; and

FIG. 8 is a fragmentary section view showing juncture of the gas conducting tube with the gas tube receptacle of the gas block and showing the presence of a sealing ferrule within a seal receptacle surrounding the gas tube receptacle.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

Referring now to the drawings and first to FIGS. 1 and 2, there is shown a firearm barrel assembly generally at 10 having a barrel 12 that is provided with a barrel mounting and alignment extension 14 having an indexing pin 16 that engages within an indexing receptacle of an upper receiver and precisely orients the firearm barrel with respect to the upper receiver of a semi-automatic firearm, such as an AR-15 tactical rifle. The barrel is provided with a circular retainer flange 18 that is engaged by a barrel nut to retain the barrel assembly in fixed and properly oriented relation with a conventional upper receiver.

At a desired location along the length of the barrel 12 a gas block 20 is mounted in substantially fixed relation with the barrel, being secured about the external surface of the barrel by means of set screws or any other suitable retainer or locking devices. As shown in the longitudinal section view of FIG. 2 the barrel 12 defines a bore 22, typically a rifled bore, through which a fired bullet is moved by cartridge gas pressure and within which cartridge gas is developed upon firing of a cartridge within a cartridge chamber of the barrel. Conventionally, for cartridge gas pressure operation of the firearm, a gas port 24 communicates the bore 22 of the barrel with a passage 26 of the gas block 20. The internal gas passages of the gas block are in communication with a gas tube receptacle or passage 28 that faces the upper receiver of the firearm. If desired, the barrel may be provided with one or more additional gas ports 25 and a port selector mechanism such as set forth in U.S. Pat. No. 8,393,259, issued to Mark C. LaRue on Mar. 12, 2013.

A conventional gas conducting tube 31 has an end portion thereof located in within the gas tube receptacle 28 and defines a gas passage 33 that serves to conduct the cartridge gas pressure from the gas block to a bolt carrier and bolt actuating mechanism of the firearm. Cartridge gas communication with the gas port becomes effective, after a bullet has moved past the gas port 24 or ports 24 and 25, for the purpose of driving the bolt carrier and bolt rearwardly against the force of a bolt return or buffer spring. This rearward bolt carrier and bolt movement extracts a spent cartridge case from the cartridge chamber of the barrel and ejects the spent cartridge case and prepares the bolt carrier and bolt mechanism for spring urged forward movement of a fresh cartridge from a cartridge magazine into the cartridge chamber of the barrel. The gas tube 31 is secured within the gas tube passage 28 by a gas tube retainer 29 that extends through aligned retainer openings in the gas block 20 and gas tube 31. The gas tube retainer 29 is preferably in the form of a retainer pin, but if desired may have the form of a retainer screw or any other suitable type of retainer that secures the gas tube in substantially immoveable relation with the gas block member 20.

The barrel 12 of the firearm is machined to define a reduced diameter external cylindrical section 30 about which the gas block 20 is received. The barrel structure is also machined to define a gas passage 32, best shown in FIG. 7, which is aligned with the gas port of the barrel 12 and conducts cartridge gas pressure to the gas tube. A gas port 35 is formed in the gas tube and is in communication with the gas passage 32 for communication of the cartridge gas pressure with the internal passage 33 of the gas tube. Set screws 34 and 36 are received within internally threaded set screw openings 38 and 40 of the gas block 20 and are seated and tightened to engage the reduced diameter section 25 of the barrel 12 to retain the gas block 20 in substantially immovable relation with the barrel 12. The forward end portion of the barrel 12 is provided with a reduced diameter externally threaded section 42 to which is threaded a flash guard, sound suppressor or other barrel mounted device. The reduced diameter threaded section has an abrupt annular shoulder 44 against which a barrel mounted device can be seated if desired.

Referring now to FIGS. 3-5 and 7, a simplified version of the gas block 20 is shown to be of generally tubular form, and defines an internal passage 46 that receives the cylindrical section 30 of the barrel 12 in close fitting relation. The set screws 34 and 36 are received within the threaded openings 38 and 40 of a thickened portion or boss 48 that is located at the bottom portion of the gas block 20 as shown in FIG. 7 and are tightened against the cylindrical portion 30 of the barrel to secure the gas block in immoveable relation with the barrel.

The upper portion of the gas block is also defined by a boss or thickened section 50 which is drilled or otherwise machined to define a gas tube bore 52 within which the rear end section of the gas conducting tube 31 is received. Holes 54 are formed in the gas tube, as shown in FIGS. 5 and 7, which become aligned with retainer holes 56 of the gas block member 20, permitting a retainer member such as a pin or screw to be extended into the aligned holes to retain the gas conducting tube within the gas tube bore 52 of the gas block member and define a gas block/gas tube unit. With the gas conducting tube in place within the gas block, the sealing ferrule is press-fitted into its receptacle, thus slightly deforming the thin sealing material and establishing positive sealing with the gas block. When so positioned, the gas communication port 35 of the gas conducting tube is aligned with the gas passage 32 of the gas block 20.

With reference to FIGS. 5, 7 and 8, the gas block 20 defines a counter bored seal receptacle 58, within which is received a gas sealing ferrule 60 that establishes sealing within the seal receptacle and with the outer cylindrical surface 62 of the gas conducting tube 31. The counter bored seal receptacle 58 defines an internal annular seal stop shoulder 59 that is contacted by the inner annular end of the gas sealing ferrule 60 when the gas sealing ferrule has been inserted to its full extent within the seal receptacle. The gas sealing ferrule is preferably composed of a thin deformable metal material, though it may be composed of a durable heat resistant polymer material or any other sealing material that is suitable for the intended purpose. The gas sealing ferrule 60 has an opening 64 that receives the gas tube 31 in relatively close fitting relation and defines an annular tapered lead end 66 to enable guided entry of the cylindrical tubular portion 68 of the ferrule into the counter-bored seal receptacle 58. The seal receptacle 58 defines a seal flange receptacle 70, being a part of the annular gas sealing receptacle within which a circular flange 72 of the sealing ferrule 60 is received. The seal flange receptacle 70 also assists the sealing capability of the ferrule seal by receiving the circular flange 72 and defining a relatively large flange surface area that serves as an outer flange stop or location shoulder for the annular sealing ferrule and enhances the physical dimension and sealing capability of the sealing ferrule as the result of the press-fitting operation.

Sealing Ferrule Installation: When connection of the gas conducting tube 31 with the gas block 20 is initiated, the gas sealing ferrule 60 is positioned over the gas tube 31 and is moved to a desired position along the length of the gas tube. The rear end portion of the gas tube is then inserted into the counter-bored seal receptacle 58 with its gas communication port 35 aligned with the gas passage 32 of the gas block. A retainer pin, screw or other suitable retainer is then inserted through the aligned holes 54 and 56 of the gas conducting tube and gas block to retain the gas conducting tube in assembly within the tube receptacle of the gas block. The gas sealing ferrule 60 is moved into the counter-bored seal receptacle 58 to establish positive gas sealing with the internal surfaces that define the seal receptacle 58 and with the gas conducting tube 31. The tapered annular lead end 66 of the gas sealing ferrule serves to guide the cylindrical portion of the gas seal ferrule into the counter-bored seal receptacle 58. When inserted to its full extent within the counter-bored seal receptacle 58 the annular tapered lead end of the gas sealing ferrule can come into contact with the annular internal stop shoulder 59, thus stopping linear insertion movement of the gas sealing ferrule and assisting in deformation of the gas sealing ferrule to establish positive sealing. The press-fitting operation also causes the circular flange 72 to enter its circular recess 70 and contact the outwardly facing annular shoulder 71, thus limiting further linear movement of the sealing ferrule during its press-fitting operation.

Typically press-fitting of the gas sealing ferrule 60 may be accomplished by placing the gas block 20 within a fixture and using a press to move the gas sealing ferrule linearly along the gas tube and into the seal receptacle with sufficient force for press fitting the gas sealing ferrule. The press-fitting activity typically causes slight deformation of the material from which the gas sealing ferrule is composed and causes it to establish positive surface to surface sealing engagement with both the seal receptacle 58 and the outer cylindrical surface of the gas conducting tube 31. Thus, when the firearm is subsequently fired, the high gas pressure of the resulting cartridge gas will be contained against any possibility of leakage at the gas block and gas tube interface as the cartridge gas pressure traverses the gas conducting tube and increases the pressure within the gas passages of the upper receiver of the firearm. Virtually all of the cartridge gas pressure that is generated upon cartridge firing is employed for bolt and bolt carrier operation and cartridge cycling.

From the foregoing description and drawings it is evident that the present invention is one well adapted to attain all of the objects and features hereinabove set forth, together with other objects and features which are inherent in the apparatus

As will be readily apparent to those skilled in the art, the present invention may easily be produced in other specific forms without departing from its spirit or essential characteristics. The present embodiment is, therefore, to be considered as merely illustrative and not restrictive, the scope of the invention being indicated by the claims rather than the foregoing description, and all changes which come within the meaning and range of equivalence of the claims are therefore intended to be embraced therein. 

1. A cartridge gas actuating mechanism for a firearm comprising: a barrel defining a barrel bore and having a barrel port along the length thereof in communication with said barrel bore; a gas block member being mounted externally of said barrel and having a gas passage in communication with said barrel port; a gas tube receptacle being defined within said gas block member; a gas conducting tube having an internal gas passage and having an end portion thereof retained within said gas tube receptacle and establishing a gas block/gas tube interface; and a seal member establishing positive sealing within said gas tube receptacle and with said gas tube and with said gas block member at said gas block/gas tube interface and preventing leakage of cartridge gas from said gas block/gas tube interface upon firing of a cartridge.
 2. The cartridge gas actuating mechanism of claim 1, comprising: said seal member being an annular seal member positioned about said gas conducting tube and being press-fitted within said gas tube receptacle to establish positive sealing with said gas block and said gas conducting tube at said gas block/gas tube interface.
 3. The cartridge gas actuating mechanism of claim 1, comprising: an annular gas seal receptacle being defined by said gas block member and surrounding said gas tube receptacle; and said seal member being an annular ferrule seal located within said annular gas seal receptacle and having sealing engagement with said gas block member within said annular gas seal receptacle and having sealing engagement with said gas conducting tube.
 4. The cartridge gas actuating mechanism of claim 3, comprising: said annular gas seal receptacle having a substantially cylindrical internal wall surface and having an outer enlargement defining a circular receptacle having a generally circular seal flange receptacle circumscribing said gas tube receptacle; said gas tube being substantially immoveable relative to said gas block member and being composed of metal and having a generally cylindrical external configuration; said annular ferrule seal member being composed of deformable metal and having a generally cylindrical wall and having an annular tapered lead end enabling guided entry of said generally cylindrical wall into said annular gas seal receptacle during press fitting installation, said annular ferrule seal member being press-fitted within said annular gas seal receptacle and being deformed sufficiently by press-fitting force to establish positive sealing thereof with said gas block within said annular gas seal receptacle and with said gas conducting tube.
 5. (canceled)
 6. The cartridge gas actuating mechanism of claim 4, comprising: said annular ferrule seal member being composed of deformable metal material and having a central opening receiving said gas conducting tube; upon being deformed by press-fitting said annular ferrule seal member establishing positive cartridge gas pressure resistant sealing within said gas tube receptacle of said gas block member and with said gas conducting tube; and said annular ferrule seal member having an outer circular flange being positioned within said seal flange receptacle.
 7. The cartridge gas actuating mechanism of claim 1, comprising: a gas tube bore being defined by said gas block and having an end portion of said gas conducting tube substantially fixed therein; said gas tube receptacle being located in substantially concentric relation with said gas tube bore and being of generally cylindrical internal configuration and having a gas passage being aligned with said barrel port of said firearm barrel and communicating cartridge gas from said barrel port into said gas conducting tube; an annular gas seal receptacle being defined by said gas block and having an inner receptacle surface portion being located substantially concentrically about said gas tube receptacle and having an annular internal stop shoulder; and said seal member being a ferrule seal having a generally cylindrical tubular portion being received within said annular gas seal receptacle about said gas tube and establishing a seal with said gas tube and a seal with said gas block within said inner receptacle surface of said annular gas seal receptacle.
 8. The cartridge gas actuating mechanism of claim 7, comprising: an annular seal flange receptacle being defined by said gas block about said gas tube receptacle and having an annular flange shoulder; and an annular flange being defined by said ferrule seal and being received by said annular seal flange receptacle.
 9. The cartridge gas actuating mechanism of claim 8, comprising: said gas block member defining an external surface intersected by said annular flange seal receptacle; and said annular flange of said ferrule seal being positioned within said annular flange seal receptacle and being located substantially coextensive with said external surface.
 10. A cartridge gas actuating mechanism comprising: a barrel defining a barrel bore and having a barrel port along the length thereof in communication with said barrel bore; a gas block member being mounted externally of said barrel and having a gas passage in communication with said barrel port; a gas tube receptacle being defined within said gas block member; a gas conducting tube having an internal gas passage and having an end portion thereof retained within said gas tube receptacle and establishing a gas block/gas tube interface, said gas conducting tube having an end portion thereof fixed within said gas tube receptacle and defining a gas port being in alignment with said gas passage; a gas seal receptacle being defined by said gas block member and being open to said gas tube receptacle, said gas seal receptacle having a generally cylindrical wall section and a gas seal flange receptacle circumscribing said generally cylindrical wall section; and a seal member being press-fitted within said gas seal receptacle and having a generally cylindrical wall in sealing engagement with said generally cylindrical wall section and having a substantially circular flange member positioned within said gas seal flange receptacle, said seal member establishing positive sealing with said gas tube and with said gas block member within said gas seal receptacle and preventing leakage of cartridge gas at said gas block/gas tube interface upon firing of a cartridge.
 11. The cartridge gas actuating mechanism of claim 10, comprising: said gas seal receptacle being defined by said gas block member and being located in substantially concentric relation with said gas tube receptacle; said gas conducting tube having a generally cylindrical external surface; and said seal member being an annular ferrule seal located within said annular gas seal receptacle and being deformed by press-fitting and establishing cartridge gas pressure resistant sealing engagement with said gas block member within said annular gas seal receptacle and establishing sealing engagement with said generally cylindrical external surface of said gas conducting tube.
 12. (canceled)
 13. The cartridge gas actuating mechanism of claim 11, comprising: said annular gas seal receptacle defining a circular internal surface and a circular bottom surface in substantially concentric relation with said gas tube bore; said annular ferrule seal being composed of deformable material and having a central opening receiving said gas conducting tube; and upon being deformed by press-fitting said annular ferrule seal being conformed to and establishing sealing engagement with said circular internal surface and said circular bottom surface of said annular gas seal receptacle and establishing sealing relation with said generally cylindrical external geometry of said gas conducting tube thus establishing positive sealing with said gas block and with said gas conducting tube.
 14. The cartridge gas actuating mechanism of claim 10, comprising: said gas tube receptacle being of generally cylindrical internal configuration; an annular gas seal receptacle being defined by said gas block and having an inner cylindrical receptacle surface and an internal circular bottom shoulder both being located concentrically about said gas tube receptacle; and said seal member being a ferrule seal having a generally cylindrical tubular portion being received in sealing relation with said inner cylindrical receptacle surface and establishing a seal with said gas tube and a seal with said gas block within said annular gas seal receptacle, said generally cylindrical tubular portion having an annular tapered lead end facilitating ease of insertion of said seal member into said annular gas seal receptacle.
 16. The cartridge gas actuating mechanism of claim 14, comprising: an annular seal flange receptacle being defined by said gas block about said gas tube receptacle and having an annular flange shoulder; and an annular flange being defined by said ferrule seal and being received by said annular seal flange receptacle.
 17. The cartridge gas actuating mechanism of claim 10, comprising: said gas block defining an external generally planar surface intersected by said annular flange seal receptacle; and said annular flange of said ferrule seal having generally planar surface being located substantially coextensive with said external generally planar surface when said annular flange is seated within said annular flange seal receptacle.
 18. A cartridge gas actuating mechanism comprising: an upper receiver having a barrel defining a cartridge chamber and barrel bore and having a barrel port along the length thereof in communication with said barrel bore; a gas block member being mounted externally of said barrel and having an internal gas passage in communication with said barrel port; a gas tube receptacle being a gas tube bore defined within said gas block member; a gas conducting tube having an internal gas passage and a generally cylindrical external surface and having an end portion thereof retained in substantially fixed relation within said gas tube receptacle and establishing a gas block/gas tube interface; a gas seal receptacle being defined within said gas block member substantially concentric about said gas tube receptacle and being open to said gas tube receptacle; and an annular deformable ferrule seal member located about said gas conducting tube and being press-fitted within said gas seal receptacle and establishing positive sealing with said generally cylindrical external surface of said gas tube and with said gas seal receptacle of said gas block member and preventing leakage of cartridge gas at said gas block/gas tube interface upon firing of a cartridge.
 19. The cartridge gas actuating mechanism of claim 18, comprising: said gas seal receptacle defining an annular seal flange receptacle located in substantially concentric relation about said gas tube receptacle and intersecting an external surface of said gas block; and said annular deformable ferrule seal member having an annular flange defining an outer end thereof, said annular flange being received by said annular seal flange receptacle. 